Installation for conveying a first plurality of electrical signals carried by a first triaxial cable to a second triaxial cable

Abstract

The present invention relates to an installation for conveying electrical signals carried by a first triaxial cable ( 1 ) to a second triaxial cable ( 18 ). It comprises: a first interface ( 15 ) between the first triaxial cable ( 1 ) and a fiber optic cable ( 9 ) and a second interface ( 16 ) between the fiber optic ( 9 ) cable and the second triaxial cable ( 18 ). A television camera ( 17 ) is connected to a remote camera control unit ( 14 ) via this installation. The first triaxial cable ( 1 ) connects CCU ( 14 ) with the interface ( 15 ). The interface ( 15 ) comprises an adapter converting electrical signals, conveyed by the triaxial cable ( 1 ), to optical signals. The fiber optic cable ( 9 ) transmits optical signals to the second interface ( 16 ). The interface ( 16 ) comprises an adapter converting optical signals to electrical signals. The second triaxial cable ( 18 ) transmits the electrical signals to the television camera ( 17 ). A mirror image of the adapters allows transmitting electrical signals from the camera ( 17 ) to the CCU ( 14 ).

1. Installation for conveying a first plurality of electrical signals carried by a first triaxial cable to second triaxial cable comprising a first adapter between the first triaxial cable and a first fibre optic cable and a second adapter between the first fibre optic cable and the second triaxial cable, wherein the first adapter comprises:
 a plurality of low pass anti-alias filters each designed to produce a filtered version of the electrical signals, 
 a plurality of analogue to digital converter circuits each connected to one of the low pass anti-alias filters, designed to produce a digital representation of each of the filtered versions of the electrical signals, 
 a first digital coding circuit connected to each of the analogue to digital converter circuits, that produces a plurality of digital signals each representing a subset of the digital representations of the electrical signals, 
 a plurality of first optical transducers each of which is designed to convert one of the digital electrical outputs from the digital coding circuit to a digital optical signal, 
 in that the first fibre optic cable is connected to the first optical transducers and comprises at least one optical fibre, in that the second adapter comprises: 
 a plurality of second optical transducers connected to the fibre optic cable, each of which is designed to convert one of the digital optical signals produced by the first optical transducers and transmitted by the first optic cable to a digital electrical signal, 
 a plurality of digital decoding circuits each fed from one of the optical transducers and reproducing a digital representation of one of the filtered versions of the electrical signals, 
 a plurality of digital to analogue converter circuits each connected to one of the digital decoding circuits and each being designed to reproduce a filtered version of the electrical signals, 
 a summing circuit combining the reproduced filtered versions of the electrical signals to reproduce the electrical signals carried by the first triaxial cable, 
 and in that the output of one or more of the digital to analogue converters connected to the digital decoding circuitry, represents more than one of the electrical signals carried on the first triaxial cable. 
 
     
     
       2. Installation according to  claim 1 , wherein the second adapter further comprises a plurality of digital filters each connected between one of the digital decoding circuits and one of the digital to analogue converters, each operating to further reduce the bandwidth of one of the digital representations of the filtered versions of the electrical signal. 
     
     
       3. Installation according to  claim 1 , wherein the first adapter further comprises a plurality of digital filters each connected between one of the analogue to digital converters and the digital coding circuits, each operating to further reduce the bandwidth of one of the digital representations of the filtered versions of the electrical signal. 
     
     
       4. Installation according to  claim 2 , wherein the digital filters that are adjacent in frequency range are provided with complementary transition bands so that the combined response is constant and continuous. 
     
     
       5. Installation according to  claim 1 , wherein the output of one or more of the digital to analogue converters connected to the to the digital decoding circuitry represents one of the electrical signals carried on the first triaxial cable. 
     
     
       6. Installation according to  claim 2 , wherein the digital filters are designed so that signals carried on the first triaxial cable are reproduced by the summing circuit regardless of their frequency provided only that they lie within a continuous range of frequencies. 
     
     
       7. Installation according to  claim 6 , wherein the digital filters are designed to be complementary so that the sum of the frequency response of the filters is constant across the operating frequency range. 
     
     
       8. Installation according to  claim 1 , wherein it comprises an automatic calibration circuit designed to adjust the amplitude of one or more of the analogue to digital converters to compensate for imbalances in the gains of the anti-alias filters, analogue to digital converters or their associated circuitry including drivers amplifiers and buffers. 
     
     
       9. Installation according to  claim 1 , wherein the first adapter comprises an optical combiner summing the optical signals from the first optical transducers so that they may be conveyed on a single optical fibre. 
     
     
       10. Installation according to  claim 9 , wherein the second adapter comprises a wavelength division multiplexer connected to the optical fibre and splitting the combined optical signal to connect to each of the second optical transducers. 
     
     
       11. Installation according to  claim 1 , wherein the installation is designed for conveying a second plurality of electrical signals carried by the second triaxial cable to the first triaxial cable comprising a third adapter between the second triaxial cable and a second fibre optic cable and a forth adapter between the second fibre optic cable and the first triaxial cable, the third adapter being designed as the first adapter according to  claim 1  and the fourth adapter being designed as the second adapter according to  claim 1  and in that the first and third adapters and the second and fourth adapters may not being of identical design. 
     
     
       12. Installation according to  claim 11 , wherein the frequency response of the filters and sample rates of the analogue to digital converters of the third and first adapter are different and the frequency response of the filters and sample rates of the digital to analogue converters of the second and fourth adapters are different. 
     
     
       13. Installation according to  claim 11 , wherein the first and fourth adapters respectively the second and the third adapters are enclosed in two different housings provided with input and output ends connected to the triaxial and fibre optic cables. 
     
     
       14. Installation according to  claim 11 , wherein the first and fourth adapters are connected to triaxial cable carrying electrical signals from and to a camera control unit (CCU) while the second and third adapters are connected to a triaxial cable carrying electrical signals to and from a television camera. 
     
     
       15. Installation according to one of  claim 11 , wherein the fibre optic cable is a hybrid cable comprising two optical fibres and copper conductors, in that the first adapter is provided with a power diplexer fed by the first triaxial cable and designed to allow DC or AC power to flow to copper conductors for power supplying devices located at the distal end of the hybrid cable and/or of distal end of the second triaxial cable. 
     
     
       16. Installation according to  claim 11 , wherein the first and fourth adapters respectively the second and the third adapters are coupled to the ends of a single optical fibre by means of wavelength division multiplexers or directional couplers.